IGCSE Physics formulae Flashcards
speed
distance travelled
time taken
s =
d
t
acceleration
change in velocity
time taken
a =
(v-u)
t
Hooke’s law for springs
Force applied to a spring is proportional to its extension, up to the limit of proportionality
For a spring,
F =
kx
Resultant force on an object
mass x acceleration
or
the vector sum of all the individual forces acting on it
For an accelerating object with a resultant force on it,
F =
ma
weight
mass x gravitational field strength
W =
mg
What is the gravitational field strength at the surface of the Earth (with units)
10 N/kg
(approximately)
density
mass
volume
**ρ = **
m
V
moment
force x perpendicular distance to the line of action of the force
moment of a force =
Fd
The Principle of Moments
If a body is in equilibrium,
sum of clockwise moments = sum of anticlockise moments
F1d1 + F2d2….= F3d3 + F4d4…
current (in amps)
charge (in coulombs)
time (in seconds)
Q =
It
I =
Q
t
Refractive index of a material
speed of light in a vacuum
speed of light in the material
n =
sin i
sin r
Electromagnetic spectrum in order of decreasing wavelength
frequency (in Hz)
number of waves passing per second
f =
1
T
(T= the period of the, i.e. the time for one complete wave)
wave speed (in m/s)
frequency (in Hz) x wavelength (in m)
For a wave
v =
fλ
The prefix M in front of a unit means?
“mega” / million
e.g. 1Mz = 1,000,000 Hz
EGPE =
mgΔh
**EKE = **
mv2
2
Efficiency
useful energy ( x 100%)
total energy supplied
Work done against a force
force x distance moved against the force
W =
Fd
Power
energy transferred
time taken
P
E
t
E =
(in terms of power)
Pt
Pressure
force
area the force is applied over
p =
F
A
The SI units of pressure are?
pascal or newtons per square metre
Pa N/m2
p =
(due a liquid of depth of h)
hρg
Boyle’s Law for a fixed mass of gas at a constant temperature in locations 1 and 2
p1V1 = p2V2
Energy required to change state
E =
mL
Energy required to raise the temeprature of an object
E =
mc(θ1-θ2)
or
mcΔT
Units of specific heat capacity
J/(kg **°C)**
Electrical energy transferred
E =
QV
Resistance of a component in an electric circuit
Potential Difference across the component
current through the component
V =
IR
Electrical power
P =
IV
Energy transferred by an electric current
E =
ItV
The transformer equation
Vp = Np
Vs Ns
Assuming a transformer is 100% efficient, the power on either side is linked by the equation
VpIp = VsIs
For resistors in series,
Rtotal =
R1 + R2 + …
For resistors in parallel,
**1 = **
Rtotal
1 + 1 + …
R1 R2 .
The total Potential Difference across components in series the same branch of an electric circuit
= V1 + V2 + …
The sum of the currents flowing into a junction in an electric circuit
= the sum of all the currents flowing out of the junction
